1. Field of the Invention
This invention relates to an optical apparatus having a mount molded of plastic.
2. Related Background Art
Heretofore, mounts for optical apparatuses such as camera bodies, interchangeable lenses, intermediate tubes and various converters have been made by cutting and machining a metallic material.
On the other hand, it has been proposed in Japanese Laid-Open Utility Model Application No. 55-138628 to mold a mount of plastic for an optical apparatus for an interchangeable lens. According to this, a mount for an optical apparatus can be provided inexpensively.
As a practical matter, however, it has been difficult for the following reasons to use a mount for an optical apparatus molded of plastic as a product:
(1) If a material with excellent sliding capability is used with importance attached to the operability of mounting or dismounting a mount, the mechanical strength of the mount will become weak and the mount will be readily damaged when a force is applied to a lens barrel or the like. Also, if too large a quantity of a reinforcing material such as glass fiber is added to increase the strength of plastic, the operability of mounting or dismounting the mount will become worse.
(2) During molding, burrs are produced on the parting lines of a metal mold and if these burrs lie at a locations which are important in surface accuracy, the optical performance will become worse.